Modern planetary automatic transmissions have relatively complex arrangements including multiple planetary gearsets in order to achieve varying speed ratios while still providing a compact overall arrangement. The need to provide improved ratios and outputs for planetary automatic transmissions has increased the relative speeds of the transmission components significantly. These increase demands have increased the need to provide a relatively high volume of lubrication to the transmission elements, such as the rolling elements between an associated planetary gear and pinion shaft.
Known solutions for providing lubricant to these planetary arrangements have included designing a more complicated and expensive planetary staking pin. These known planetary staking pins require specialized formation techniques to provide a localized hardened portion to support the rolling elements. However, the axial ends of the pins must be relatively softer to facilitate axial fixation of the pin to a corresponding planetary carrier through staking or riveting. These known pins typically include internal lubrication passages that are drilled into the pin's body to direct lubricant from the planetary carrier to a load zone of the rolling elements.
FIGS. 1A and 1B illustrate known arrangements for a planetary transmission 100a, 100b. As shown in these planetary transmissions 100a, 100b, a planetary staking pin 110a, 110b includes an internal lubrication passage 120a, 120b for directing lubrication from a planetary carrier 130a, 130b to rolling elements 140a, 140b supporting a planetary gear 150a, 150b. FIG. 1C illustrates a flowpath of lubrication for the type of arrangements of FIGS. 1A and 1B.
FIG. 2A-2D illustrate a known type of planetary staking pin 110c. The planetary staking pin 110c includes a lubricant inlet 112 proximate to an axial end of the pin 110c, a lubricant outlet 114 in a medial portion of the pin 110c, and a localized hardened zone 116 in a medial region of the pin 110c for forming a raceway for associated rolling elements. Creating the geometry for this type of planetary staking pin 110c is relatively complicated and expensive.
These known types of planetary staking pins 110a, 110b, 110c require a complicated and expensive planetary pin blank that requires special geometrical features to accommodate the necessary heat treatment process. There are competing needs of the planetary pin to have both (a) relatively softer ends to allow for staking the associated planetary carrier, and (b) a relatively harder medial portion to provide a raceway for rolling elements.
Accordingly, there is a need for a planetary staking pin that is relatively easy to assemble and inexpensive, that also provides the requisite structural characteristics to allow staking at its axial ends and provide a suitable rolling element raceway.